基于双“泥质指示因子”的砂泥岩薄互层饱和度模型

砂泥岩薄互层的电阻率受泥岩影响,导致直接应用阿尔奇公式计算的含油饱和度偏低.针对砂泥岩薄互层内部沉积结构特征,将储层看作多个不同岩性薄层交互分布的层状介质,考虑层间耦合与层内泥质的共同导电效应,提出了一种横向、纵向双"泥质指示因子"导电等效模型,由此建立了砂泥岩薄互层饱和度计算模型.通过处理分析实际测井资料可知,利用该模型计算的含水饱和度比阿尔奇公式计算结果低10%~20%,更接近于岩心试验分析结果.研究表明,新建立的饱和度模型可降低薄互层层内及层间泥质对含水饱和度计算的影响,适用于砂泥岩薄互层测井资料的处理解释,对于厚砂岩层同样适用. 

Thin Sand and Mudstone Interbed Saturation Model Based on a Dual Mudstone Indicator

The resistivity of thin sand and mudstone interbeds is affected by mudstone, so that oil saturation calculated directly by Archie equation is lower. The reservoir can be considered as a layered medium with cross distribution of various thin layers based on internal sedimentary structural characteristics of thin sand and mudstone interbeds. Considering common electric conduction effect of interlayer coupling and a mudstone layer, a horizontal-vertical dual mudstone indicator conductive equivalent model is proposed. Thus, a computation model is built for thin sand and mudstone interbed saturation. According to processing and analysis of actual logging data, the water saturation calculated from the model is 10% to 20% lower than that calculated by the Archie equation which is closer to core test data. Research results show that the new saturation model can reduce effects on water saturation calculation of inter-layer and intra-layer mudstone of thin interbeds. It is applicable logging data interpretation for thin sand and mudstone interbed as well as thick sandstone.